Details of the CATV modulator are well known to persons skilled in this art and can be located from many prior documents describing the operation of these arrangements. Extensive details are available in the Technical Reports available from Cable Television Laboratories Inc and particularly the reports entitled
Data-Over Cable Service Interface Specifications Modular Headend Architecture which is CM-TR-MHA-V02-081209 copyright 2008; and
Data-Over Cable Service Interface Specifications which is CM-TR-CMAP-V01-101222 copyright 2010.
These documents are published and available on line from their web site at Cablelabs.com. The disclosure of the above documents is hereby incorporated by reference.
In an analog CATV or QAM service deployment, it is often necessary to combine the outputs of multiple upconversion paths in order to meet the transmission bandwidth needs of a particular node or service group. Switching of signals or data is performed prior to the upconversion process. External RF switching or combination of the upconverted channel groups is also performed. This system of switching and combination does not allow for the dynamic reassignment of channels to the available upconversion paths or “ports”, nor does it allow for the aggregation of the total channel capacity of the system to one port.
Another characteristic weakness of this approach is that of failover. Typically, redundant upconversion modules are present in the deployment and are switched into the signal path upon the detected failure of another upconversion module. This process of failing over to an alternate upconversion path is relatively slow and results in a loss of data or interruption of service.